Organophosphorus and metal organophosphorus compounds are used extensively in lubricating oils and greases as extreme pressure agents and anti-wear agents. Examples of such compounds include: phosphosulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine; phosphorus esters including dihydrocarbon and trihydrocarbon phosphites; and metal phosphorodithioates such as zinc dialkylphosphorodithioates.
Hydraulic fluid compositions, particularly automatic transmission fluid compositions, containing a phosphite or a di-substituted phosphate in combination with other additives is described in U.S. Pat. No. 3,556,999. The phosphites my be mono-, di- or tri-substituted phosphites, and where the substituent is an alkyl group. The alkyl group may be present in any of its known configurations such as normal, iso, or tertiary. Other patents describing the use of phosphites, including dialkyl hydrogen phosphites in lubricating formulations include, for example, U.S. Pat. Nos. 3,115,465; 4,029,587; 4,029,588; 4,031,023; 4,116,877; 4,146,489; 4,160,739; 4,161,452; and 4,256,596.
It also is well known that many sulfurized organic compositions are useful as lubricant additives. Typical sulfurized compositions prepared by reacting olefins such as isobutene, diisobutene, and triisobutene with sulfur under various conditions are described in, for example, Chemical Reviews, 65, 237 (1965). Other references describe the reaction of such olefins with hydrogen sulfide to form predominantly mercaptans with sulfides, disulfides and higher polysulfides also being formed as by-products. Reference is made to J. Am. Chem. Soc., 60, 2452 (1938), and U.S. Pat. No. 3,419,614. The patent describes a process for increasing the yield of mercaptan by carrying out the reaction of olefin with hydrogen sulfide and sulfur at a high temperature in the presence of various basic materials.
It also has been known that Diels-Alder adducts can be sulfurized to form sulfur-containing compositions which are particularly useful as extreme pressure and anti-wear additives in various lubricating oils. U.S. Pat. Nos. 3,632,566 and Re. 27,331 describe such sulfurized Diels-Alder adducts and lubricants containing said adducts. In these patents, the ratio of sulfur to Diels-Alder adduct is described as being a molar ratio of from about 0.5:1.0 to 10.0:1.0. The disclosed lubricating compositions may contain other additives normally used to improve the properties of lubricating compositions such as dispersants, detergents, extreme pressure agents, and additional oxidation and corrosion-inhibiting agents, etc.
U.S. Pat. No. 4,191,659 describes the preparation of sulfurized olefinic compounds by the catalytic reaction of sulfur and hydrogen sulfide with olefinic compounds containing from 3 to 30 carbon atoms. Such compounds are reported to being useful in lubricating compositions, particularly those prepared for use as industrial gear lubricants. U.S. Pat. No. 4,119,549 describes a similar procedure for sulfurizing olefins, particularly fatty acids, utilizing sulfur and hydrogen sulfide following by removal of low boiling materials from said sulfurized mixture.
Other sulfurized compositions of matter also have been suggested as compositions useful as additives for lubricants. U.S. Pat. No. 2,012,446 describes a method of sulfurizing pine oil which is reported as being useful as an additive for lubricant manufacture. U.S. Pat. No. 3,953,347 describes a sulfurized composition of matter which is prepared by reacting sulfur with a mixture of at least one fatty acid ester of a polyhydric alcohol, at least one fatty acid and at least one aliphatic alpha-olefin. These latter compositions are suitable as replacements for sulfurized sperm oil as extreme pressure additives in lubricants. U.S. Pat. No. 4,584,113 describes sulfurized compositions prepared by sulfurizing a mixture of at least one terpene (e.g., pine oil) and at least one other olefinic compound. These sulfurized compositions are useful in lubricants, particularly industrial and gear lubricants.
The preparation of hydroxythioethers and their use in lubricating oil compositions is described in U.S. Pat. No. 4,031,023. The lubricating compositions containing the described hydroxythioethers exhibit increased resistance to oxidative degradation and wear. Other patents including descriptions of the preparation of suitable hydroxythioethers include U.S. Pat. Nos. 2,570,050; 2,776,997; and 2,863,799.
Sulfurized Mannich condensation products made from phenolic compounds, aldehydes and amines have been described in U.S. Pat. No. 4,161,475, and the use of such condensation products in lubricating oils are suggested therein. The sulfurized products are obtained by reacting the Mannich condensation products with elemental sulfur. Often techniques for sulfurizing Mannich condensation products, and the prior art disclosing such procedures is summarized in U.S. Pat. No. 4,161,475. U.S. Pat. No. 3,600,372, for example, describes the treatment of Mannich condensates with carbon disulfide.
The increasing demands for improved effectiveness of lubricants and functional fluids, as well as the increasingly severe conditions under which such materials are expected to perform requires a continuing search for new and improved additives, particularly additives which are capable of performing more than one function. For example, it is important that additives useful as extreme pressure additives also exhibit good frictional characteristics. Some additives are known which perform very well as extreme pressure additives but are weak from a frictional characteristic standpoint. Similarly, some additives exhibit acceptable frictional characteristics but are deficient in extreme pressure properties.